Git Basics — Install, init, add, commit, status, log and diff

Git keeps the full history of your code. You can see what changed, when and why, go back to any earlier version, and work with a team without overwriting each other's work. Every software company uses it — and recruiters look at your GitHub profile.

1. Install and configure (once)

Download from git-scm.com (Windows) or sudo apt install git (Linux). Then tell Git who you are:

git config --global user.name "Asha Verma"
git config --global user.email "asha@example.com"
git config --global init.defaultBranch main

2. The three areas

Staging lets you commit related changes together, even if you edited many files.

3. Everyday commands

mkdir portfolio && cd portfolio
git init                       # start tracking this folder
echo "# My Portfolio" > README.md
git status                     # what changed? what is staged?
git add README.md              # stage one file (git add . = everything)
git commit -m "Add README"     # save a snapshot with a message
git log --oneline              # history, one line per commit

a1b2c3d (HEAD -> main) Add README

(Commit ids — "hashes" — will be different on your computer.)

See exactly what changed

git diff              # unstaged changes
git diff --staged     # staged changes (what will be committed)
git show a1b2c3d      # one commit's changes

4. Commits are a chain of snapshots

Each commit has a unique id, an author, a time, a message and a pointer to its parent. HEAD marks the commit you're on.

5. Good commit messages

• Short summary in the imperative: "Add login form", "Fix price rounding" (not "added stuff").
• One logical change per commit.
• Commit often — small commits are easy to understand and undo.

6. .gitignore: files Git should never track

Create a .gitignore file:

node_modules/
.env
*.log
dist/
__pycache__/

Never commit secrets (passwords, API keys, .env files). Once pushed to GitHub, assume they're leaked — rotate them immediately.

Common mistakes

• Running git init in your home folder (it tracks everything!).
• Huge commits with messages like "update".
• Committing node_modules or .env.

Quick recap

• Configure name and email once.
• Working directory → git add → staging → git commit → repository.
• status, diff, log --oneline, show to look around.
• Small commits, clear messages, .gitignore for build files and secrets.